1. Field of the Invention
The present invention relates to a texture mapping method, a recording medium, a program, and a program executing apparatus which make it possible to easily map a texture such as a light point texture indicative of a light, for example, on an image (video image) generated by a three-dimensional computer graphics (CG) technique or the like.
2. Description of the Related Art
A conventional technique for mapping a texture such as a light point texture onto an image (video image) generated by a three-dimensional computer graphics technique will be described with reference to a flowchart shown in FIG. 12.
Processes shown in the flowchart are performed by executing a three-dimensional modeling application program installed in a personal computer (hereinafter simply referred to as the PC).
Firstly, a desirable three-dimensional model is generated by the PC in step S1.
Then, a plurality of different light point textures are also generated by the PC in step S2.
Next, a process of mapping a light point texture onto the three-dimensional model generated in step S1 (texture mapping process) and a process of confirming the texture mapping process are performed in steps S3a through S3d of step S3.
Specifically, in step S3a, the three-dimensional model and the light point textures are displayed on a monitor as a display. A user selects a desirable light point texture to be mapped onto the three-dimensional model from the light point textures. Then, the user inputs data indicative of a position (coordinates) for mapping the selected light point texture onto the three-dimensional model, and data (RGB numeric values) indicative of a color of the selected light point texture, using a keyboard or the like.
Then, in step S3b, a rendering process, i.e., the texture mapping process is performed by mapping the light point texture generated in step S2 onto the three-dimensional model based on the position (coordinate) data and the color data.
Next, in step S3c, a video image generated in the rendering process is displayed on the monitor.
In step S3d, the user visually confirms whether the generated video image is suitable or not. If the generated video image is not suitable, that is, if the color or the mapping position of the light point texture is not suitable, control passes back to step S3a. In step S3a, the user inputs data again for adjusting the position and the color of the light point texture (numeric value correcting operation).
In this manner, the light point texture mapping process and the confirmation process thereof in step S3 are repeated until the user visually confirms that the generated video image is suitable in step S3d. 
However, in the conventional method of mapping a light point texture as described above, the position of the light point can not be confirmed until the video image generated in the rendering process in step S3b is actually displayed on the screen of the monitor.
Further, it is necessary to input numeric data or corrected numeric data indicative of a desirable position (coordinates) on the three-dimensional model for each light point using the keyboard or the like. Therefore, when there are many light points, a large amount of time is required for data inputting operation.
Further, when a realistic image of stars in the sky or a night view of a large city is to be drawn by the light texture mapping process, hundreds of, hundreds of thousands of light point textures are required. However, conventionally, such a large number of light point textures can not be processed in a frame time, i.e., 1/60 sec., for example, owing to the limited capability of hardware.
As described above, according to the light point texture mapping method of the conventional technique, excessively large amount of effort and time are required for designating many light points on a three-dimensional model. Further, the number of textures used for mapping is limited owing to the limited capability of hardware.